Here are some other sampling techniques.

• Experiments: An experiment is performed where a treatment is given to a sample and reactions are recorded. The sample may be split up into groups, with one group receiving the treatment, and the other group receiving nothing or a placebo (an unmedicated treatment that looks like the real one). This second group is called the control group.
• Simulations: A simulation is the use of a physical or mathematical model to reproduce certain conditions. For instance, the use of dummies to study the effects of automobile crashes on humans.

Note that the Sample Size Calculator is located in Tools. Here are some observations about sample size.

• To decrease the width of the confidence interval, increase the sample size.
• When the population is more spread out (the standard deviation is large), you will need a larger sample size than for a population that is less spread out.
• When the confidence level increases, the sample size increases.

Before you buy a new men's product at the store, you may want to consider visiting a site like coolfreebielinks.com, which offers links to numerous websites that give away free samples. There are many websites that offer free samples for both men and women. Do a Google search for "free men's products" or "free women's products" to find a site that has a product you're looking for.

Sample answer:

To conduct the survey, you could call men and ask their opinions about men's health care products. It is important to survey enough people so that you can identify which subpopulations are most likely to use men's personal care products and what type of personal care products those subpopulations are most likely to use. Only surveying the minimum sample size may not give you enough information about the opinions of all the subpopulations, so you may want to increase the number of people you survey. Information about demographics and trends can be very valuable from a marketing standpoint. If you want to advertise your products in commercials and magazines, you need to know your target audience.